This application seeks to provide support for the ascertainment, clinical and radiographic definition, and determination of the inheritance pattern in skeletal dysplasia families in Pakistan. In selected families with novel phenotypes, blood collection for molecular genetic studies will also be undertaken. The proposal seeks to broaden and deepen an ongoing collaborative effort between research groups at Cedars-Sinai Research Institute and Quaid-i-Azam University in Pakistan. In doing so, the proposed work will both expand and enhance the research efforts of the parent grant. The work will be accomplished under the following Specific Aim: 1. To describe the clinical and radiographic phenotypes and the inheritance patterns in skeletal dysplasias of Pakistan and, in a subset of families, to identify the chromosomal location of and isolate the disease genes. We will test the hypothesis that these disorders represent novel phenotypes that, once identified, will be recognized in other populations. Molecular investigations are expected to reveal novel loci and genes important for skeletogenesis. In Pakistan, the importance and understanding of genetic disorders is in its infancy, and this collaboration will allow the flow of information and resources that can be applied in caring for Pakistani families with inherited disorders. Linkage and mutation analysis data will be useful in identifying carriers of recessive and X-linked disorders in individual family members and within subsets of the population. The results will also benefit families with identical or related phenotypes in other populations.